Sealed Structure, Light-Emitting Device, Electronic Device, And Lighting Device

ABSTRACT

A sealed structure which has high sealing capability and whose border can be slim is provided. The sealed structure includes a pair of substrates whose respective surfaces face each other with a space therebetween, and a glass layer which is in contact with the substrates, defines a space between the substrates, and has at least one corner portion and side portions in continuity with the corner portion. The width of the corner portion of the glass layer is smaller than or equal to that of the side portion of the same. The sealed structure may comprise a highly reliable light-emitting element including a layer containing a light-emitting organic compound provided between a pair of electrodes.

This application is a continuation of copending U.S. application Ser.No. 16/514,141, filed on Jul. 17, 2019 which is a divisional of U.S.application Ser. No. 14/972,657, filed on Dec. 17, 2015 (now U.S. Pat.No. 10,361,392 issued Jul. 23, 2019) which is a continuation of U.S.application Ser. No. 13/687,656, filed on Nov. 28, 2012 (now U.S. Pat.No. 9,216,557 issued Dec. 22, 2015) which are all incorporated herein byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a sealed structure using a pair ofsubstrates and a glass layer. Further, the present invention relates toa light-emitting device, an electronic device, and a lighting deviceeach using organic electroluminescence (hereinafter also referred to asEL).

2. Description of the Related Art

In recent years, development of light-emitting devices and displaydevices has been actively promoted, and improvements in reliability andyield, a reduction in device size, a reduction in area except alight-emitting region (display region) (so-called a slim border), andthe like have been demanded.

Thus, a sealed structure whose border can be slim, in which the area foran object to be sealed is large has been demanded.

A sealed structure with high sealing capability can be used suitably fora display device or a light-emitting device in which a display element,a light-emitting element, or the like is an object to be sealed.

In particular, in a light-emitting device, an element whose propertiessuch as reliability are rapidly deteriorated by exposure to the aircontaining moisture or oxygen, such as a light-emitting element usingorganic electroluminescence (also referred to as an organic EL element),is preferably provided inside a sealed structure with high sealingcapability.

Patent Document 1 discloses an organic EL panel in which a substrate anda sealing substrate are attached to each other with an adhesive layer.

REFERENCE

Patent Document 1: Japanese Published Patent Application No. 2011-81944

SUMMARY OF THE INVENTION

As an example of an adhesive for attaching a pair of substrates, resinsuch as a light curing resin or a heat curing resin is known. Uponattachment of the pair of substrates, the shape of the resin sandwichedby the pair of substrates is changed to, for example, increase its widthby crush. That is, the shape of the resin provided over one of thesubstrates is different between before and after the attachment.

For example, in the case where the application quantity of the resin islarge, the resin may spread out of its predetermined region onattachment not only to disturb achievement of a slim border but also tobe mixed into a region where an object to be sealed is provided, wherebythe object is contaminated. To the contrary, too much reduction inapplication quantity of the resin in order to suppress the spread out ofits appropriate region and achieve a slim border may lead to a lack ofsufficient resin in its region after the attachment (the object cannotbe sealed enough in some cases).

One object of one embodiment of the present invention is to provide asealed structure which has high sealing capability and whose border canbe slim.

Further, one object of one embodiment of the present invention is toprovide a highly reliable light-emitting device whose border can beslim, in which an organic EL element is sealed by the sealed structure.

Still further, one object of one embodiment of the present invention isto provide a highly reliable electronic device or a highly reliablelighting device whose border can be slim and which uses thelight-emitting device.

A sealed structure of one embodiment of the present invention includes apair of substrates respective surfaces of which face each other with aspace therebetween, and a glass layer which is in contact with both ofthe substrates, defines a space between the substrates, and has at leastone corner portion in continuity with side portions. The width of thecorner portion of the glass layer is smaller than or equal to that ofthe side portion of the same.

In this specification, the interval between an inner contour and anouter contour of the glass layer is referred to as the width of theglass layer. In this specification, for example, the interval betweenthe inner contour and the outer contour in the corner portion (sideportion) of the glass layer is referred to as the width of the cornerportion (side portion).

With the above-described structure, a sealed structure which has highsealing capability and whose border can be slim can be achieved.

Spreading of the adhesive out of its appropriate region upon attachmentcan be more suppressed in the sealed structure by using the glass forattaching the pair of substrates than in the case of using resin.Accordingly, a slim border of the sealed structure can be achieved.

Further, the sealing capability of glass is higher than that of resin,and thus glass is preferable. In addition, glass is less likely to bedeformed on attachment, and thus the shape of the glass layer afterattachment can be predicted before the attachment, which enablessuppression of generation of such a defect that the glass layer does notexist in its predetermined region after the attachment and thus anobject to be sealed cannot be sealed enough. Accordingly, a sealedstructure with high sealing capability can be manufactured at highyield.

Further, the glass layer (or glass frit, frit paste, or the like forforming the glass layer) can be provided over the substrate, in itsdesired shape after attachment, which leads to simplification ofmanufacturing of the sealed structure.

In fabricating or using a sealed structure, force is more likely to beapplied to a corner portion of the sealed structure, so that the pair ofattached substrates tends to be detached from each other from the cornerportion. Therefore, it is preferable that the adhesion between the glasslayer and the substrate be high in the corner portion of the sealedstructure. Specifically, in the corner portion of the glass layer, it ispreferable that a region which is not welded to the substrate be assmall as possible, and it is more preferable that the entire surface ofthe glass layer be welded to the substrate.

If the width of the corner portion of the glass layer is larger thanthat of the side portion of the same, when the side portion isirradiated with laser light with a beam diameter which is selected inaccordance with the width of the corner portion, an object sealed by thesealed structure is also irradiated with the laser light, which maydamage the object.

To the contrary, if the beam diameter of the laser is selected inaccordance with the width of the side portion, there occurs a regionwhich is not welded to the substrate in the corner portion of the glasslayer.

However, since the width of the corner portion is smaller than or equalto that of the side portion in the glass layer in the above-describedsealed structure of one embodiment of the present invention, the glasslayer can be surely welded to the substrate in the corner portion whilesuppressing damage of laser light on an object sealed by the sealedstructure. Accordingly, application of one embodiment of the presentinvention can provide a sealed structure achieving both of high sealingcapability and a slim border, in which damage of laser light on anobject sealed by the sealed structure is suppressed.

Note that the present invention encompasses not only a structure inwhich the substrate is in direct contact with the glass layer, but alsoa structure in which the substrate is in indirect contact with the glasslayer through a film provided over the substrate. In this specification,a welding (region) between the substrate and the glass layer may denotea welding (region) between the film provided over the substrate and theglass layer, depending on the structure.

A light-emitting device of one embodiment of the present inventionincludes a pair of substrates respective surfaces of which face eachother with a space therebetween, and a glass layer which is in contactwith both of the substrates, defines a region for an object to be sealedbetween the substrates, and has at least one corner portion incontinuity with side portions. The region for an object to be sealedincludes a light-emitting element (also referred to as organic ELelement) in which a layer containing a light-emitting organic compoundis provided between a pair of electrodes. The width of the cornerportion of the glass layer is smaller than or equal to that of the sideportion of the same.

With the above-described structure, a light-emitting device which hashigh reliability and whose border can be slim can be achieved.

Spreading of the adhesive out of its appropriate region upon attachmentcan be more suppressed in the light-emitting device by using the glassfor attaching the pair of substrates than in the case of using resin.Accordingly, a slim border of the light-emitting device can be achieved.

Further, the sealing capability of glass is high, whereby deteriorationof the organic EL element due to moisture, oxygen, and the like can besuppressed. In addition, glass is less likely to be deformed onattachment, and thus the shape of the glass layer after attachment canbe predicted before the attachment, which enables suppression ofgeneration of such a defect that the glass layer does not exist in itspredetermined region after the attachment and thus the object cannot besealed enough. Accordingly, a light-emitting device with highreliability can be manufactured at high yield.

Further, the glass layer (or glass frit, frit paste, or the like forforming the glass layer) can be provided over the substrate, in itsdesired shape after attachment, which leads to simplification ofmanufacturing of the light-emitting device.

Further, as described above, in the corner portion of the glass layer,it is preferable that a region which is not welded to the substrate beas small as possible, and it is more preferable that the entire surfaceof the glass layer be welded to the substrate. In addition, the organicEL element, which is provided as the object sealed by the light-emittingdevice of one embodiment of the present invention, contains a lowheat-resistant material in many cases, and thus it is not preferable forthe organic EL element to be irradiated with laser light.

However, since the width of the corner portion is smaller than or equalto that of the side portion in the glass layer in the above-describedlight-emitting device of one embodiment of the present invention, theglass layer can be surely welded to the substrate in the corner portionwhile suppressing damage of laser light on the organic EL element.Accordingly, application of one embodiment of the present invention canprovide a light-emitting device achieving both of high reliability and aslim border, in which damage of laser light on an organic EL element issuppressed.

One embodiment of the present invention is an electronic device usingthe light-emitting device. One embodiment of the present invention is alighting device using the light-emitting device. Application of thelight-emitting device enables an electronic device or a lighting devicewhich has high reliability and whose border can be slim to be achieved.

According to one embodiment of the present invention, a sealed structurewhich has high sealing capability and whose border can be slim can beprovided.

Further, a light-emitting device which has high reliability and whoseborder can be slim, in which an organic EL element is sealed by thesealed structure can be provided.

Still further, an electronic device or a lighting device using thelight-emitting device, which has high reliability and whose border canbe slim can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A1 and 1A2, FIGS. 1B1 and 1B2, and FIGS. 1C1 and 1C2 illustrate asealed structure of one embodiment of the present invention, a sealedstructure of a comparison example, and a sealed structure of acomparison example, respectively;

FIGS. 2A to 2E illustrate sealed structures of embodiments of thepresent invention;

FIGS. 3A to 3C illustrate light-emitting devices of embodiments of thepresent invention;

FIGS. 4A and 4B illustrate a light-emitting device of one embodiment ofthe present invention;

FIGS. 5A and 5B illustrate a light-emitting device of one embodiment ofthe present invention;

FIGS. 6A to 6C illustrate EL layers;

FIGS. 7A to 7E illustrate electronic devices and a lighting device ofembodiments of the present invention;

FIG. 8 illustrates lighting devices of embodiments of the presentinvention;

FIGS. 9A to 9C illustrate an electronic device of one embodiment of thepresent invention; and

FIGS. 10A to 10C illustrate a sealed structure of one embodiment of thepresent invention and a manufacturing method thereof.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are described in detail using thedrawings. The present invention is not limited to the followingdescription, and it will be easily understood by those skilled in theart that various changes and modifications can be made without departingfrom the spirit and scope of the present invention. Therefore, thepresent invention should not be construed as being limited to thedescription in the following embodiments. In the structures of thepresent invention described below, the same portions or portions havingsimilar functions are denoted by the same reference numerals in thedrawings, and description of the portions is not repeated.

Embodiment 1

In this embodiment, a sealed structure of one embodiment of the presentinvention is described using FIGS. 1A1 and 1A2, FIGS. 1B1 and 1B2, FIGS.1C1 and 1C2, and FIGS. 2A to 2E.

A sealed structure of one embodiment of the present invention includes apair of substrates respective surfaces of which face each other with aspace therebetween, and a glass layer which is in contact with both ofthe substrates, defines a space between the substrates, and has at leastone corner portion in continuity with side portions. The width of thecorner portion of the glass layer is smaller than or equal to that ofthe side portion of the same.

Spreading of the adhesive out of its appropriate region upon attachmentcan be more suppressed in the sealed structure by using the glass forattaching the pair of substrates than in the case of using resin.Accordingly, a slim border of the sealed structure can be achieved.

Further, the sealing capability of glass is higher than that of resin,and thus glass is preferable. In addition, glass is less likely to bedeformed on attachment, and thus the shape of the glass layer afterattachment can be predicted before the attachment, which enablessuppression of generation of such a defect that the glass layer does notexist in its predetermined region after the attachment and thus anobject to be sealed cannot be sealed enough. Accordingly, a sealedstructure with high sealing capability can be manufactured at highyield.

Further, the glass layer (or glass frit, frit paste, or the like forforming the glass layer) can be provided over the substrate, in itsdesired shape after attachment, which leads to simplification ofmanufacturing of the sealed structure.

In fabricating or using a sealed structure (or a light-emitting deviceusing a sealed structure), force is more likely to be applied to acorner portion of the sealed structure, so that the pair of attachedsubstrates tends to be detached from each other from the corner portion.Therefore, it is preferable that the adhesion between the glass layerand the substrate be high in the corner portion of the sealed structure.Specifically, in the corner portion of the glass layer, it is preferablethat a region which is not welded to the substrate be as small aspossible, and it is more preferable that the entire surface of the glasslayer be welded to the substrate.

If the width of the corner portion of the glass layer is larger thanthat of the side portion of the same, when the side portion isirradiated with laser light with a beam diameter which is selected inaccordance with the width of the corner portion, an object sealed by thesealed structure is also irradiated with the laser light, which maydamage the object. Particularly in the case where a slim border isachieved and the object to be sealed is near the glass layer, the objectis more likely to be irradiated with the laser light.

To the contrary, if the beam diameter of the laser is selected inaccordance with the width of the side portion, there occurs a regionwhich is not welded to the substrate in the corner portion of the glasslayer.

Moreover, if the beam diameter of the laser is adjusted in accordancewith either the width of the side portion or the width of the cornerportion depending on the portion for irradiation, the number ofmanufacturing steps of a sealed structure is increased.

However, since the width of the corner portion is smaller than or equalto that of the side portion in the glass layer in the above-describedsealed structure of one embodiment of the present invention, the glasslayer can be surely welded to the substrate in the corner portion whilesuppressing damage of laser light on an object sealed by the sealedstructure. Accordingly, application of one embodiment of the presentinvention can provide a sealed structure achieving both of high sealingcapability and a slim border, in which damage of laser light on anobject sealed by the sealed structure is suppressed.

First, a sealed structure of one embodiment of the present invention isdescribed using FIGS. 1A1 and 1A2.

A plan view of a substrate 101 in a state just before being attached toa counter substrate is shown in FIG. 1A1. A plan view of a sealedstructure of one embodiment of the present invention is shown in FIG.1A2.

A glass layer 104 a is provided over the substrate 101 which isquadrangular as shown in FIG. 1A1 such that its inner contour is alongthe periphery of a region for an object to be sealed 102 a.

In the sealed structure of one embodiment of the present invention shownin FIG. 1A2, a glass layer 105 a is provided over the substrate 101 suchthat its inner contour is along the periphery of the region for anobject to be sealed 102 a. The substrate 101 is attached to the countersubstrate (not shown) with the glass layer 105 a. The region for anobject to be sealed 102 a is positioned in a space surrounded by thepair of substrates and the glass layer 105 a. As for the glass layer 105a, the width of a corner portion is equal to that of a side portion.

In this embodiment, the area of a surface of the substrate and that of asurface of the counter substrate which faces the surface of thesubstrate are equal to each other. For example, in the plan view of thesealed structure shown in FIG. 1A2, the shape of the counter substrateis the same as that of the substrate 101.

The region for an object to be sealed is a region where an object to besealed can be provided. Specifically, in the sealed structure of oneembodiment of the present invention, an object to be sealed can beprovided in the region for an object to be sealed 102 a over thesubstrate 101 or a region over the counter substrate which overlaps withthe region for an object to be sealed 102 a. There is no particularlimitation on the object to be sealed; for example, an organic ELelement, an element included in a plasma display, a liquid crystalelement, and the like can be given. A transistor, a color filter, or thelike may also be provided.

Manufacturing Method of Sealed Structure of One Embodiment of thePresent Invention

The glass layer 105 a in the sealed structure of one embodiment of thepresent invention can be formed of glass frit, for example. A glassribbon can also be used. The glass frit or the glass ribbon contains atleast a glass material.

The glass frit contains a glass material as a frit material; forexample, magnesium oxide, calcium oxide, strontium oxide, barium oxide,cesium oxide, sodium oxide, potassium oxide, boron oxide, vanadiumoxide, zinc oxide, tellurium oxide, aluminum oxide, silicon dioxide,lead oxide, tin oxide, phosphorus oxide, ruthenium oxide, rhodium oxide,iron oxide, copper oxide, manganese dioxide, molybdenum oxide, niobiumoxide, titanium oxide, tungsten oxide, bismuth oxide, zirconium oxide,lithium oxide, antimony oxide, lead borate glass, tin phosphate glass,vanadate glass, or borosilicate glass is contained. The glass fritpreferably contains at least one or more kinds of transition metals toabsorb infrared light.

In this embodiment, the glass layer 105 a is formed of glass frit overthe substrate 101. A manufacturing method described in this embodimentallows manufacturing of a sealed structure by which an object to besealed whose heat resistance is lower than that of the glass layer 105 a(the object is, for example, an organic EL element or a color filter) issealed. Although the manufacturing process of the object is omittedbelow, the object is provided in the region for an object to be sealed102 a over the substrate 101 or the region over the counter substratewhich overlaps with the region for an object to be sealed 102 a before astep of laser light irradiation to the glass layer 104 a.

In the case where the glass layer and the object to be sealed areprovided over the same substrate, the order of formation of thestructure and the glass layer is not limited. The glass layer and theobject may be provided over different substrates. Formation of the glasslayer may involve a heat treatment; thus, it is preferable that theglass layer and the object be provided over different substrates in thecase where the hear resistance of the object is low.

First, frit paste is applied over the substrate 101 by a printing methodsuch as screen printing or gravure printing, a dispensing method, or thelike. In particular, use of the printing method such as screen printingor gravure printing is preferable because the frit paste can be formedeasily into a desired shape. The difference between the shape of theresulting glass layer 105 a and the shape of this frit paste is small,and therefore the frit paste is preferably provided in its desired shapeafter attachment. That is, the frit paste is provided such that itsinter contour is along the periphery of the region for an object to besealed 102 a. In this embodiment, the frit paste is formed into a shapesimilar to that of the glass layer 105 a, over the substrate 101.

The frit paste contains the frit material and a resin (also referred toas a binder) diluted by an organic solvent. As for the frit paste, aknown material and a known composition can be used. For example,terpineol, n-butyl carbitol acetate, or the like can be used as theorganic solvent and a cellulosic resin such as ethylcellulose can beused as the resin. Further, an absorbent of light with a wavelength oflaser light may be contained in the frit paste.

Next, pre-baking is performed thereon to remove the resin or binder inthe frit paste, so that the glass layer 104 a is formed (FIG. 1A1).

The top surface of the glass layer 104 a is preferably flat to increasethe adhesion to the counter substrate. Thus, a planarization treatmentsuch as application of pressure may be performed thereon. Theplanarization treatment can be performed before or after the pre-baking.

Then, the substrate 101 and the counter substrate are disposed to faceeach other to make the glass layer 104 a and the counter substrate inclose contact with each other, and the glass layer 104 a is irradiatedwith the laser light. For example, the beam diameter of the laser lightis preferably greater than or equal to the width between the outercontour and the inner contour of the glass layer 104 a, because theentire surface of the glass layer 104 a can be welded to the contoursubstrate easily, whereby the sealing capability of the sealed structureof one embodiment of the present invention can be increased. Further, inthe case of using a beam diameter which is greater than that width, itis preferable that the object to be sealed be not irradiated with thelaser light.

Through the above, the sealed structure of one embodiment of the presentinvention, in which the substrate 101 and the counter substrate areattached to each other with the glass layer 105 a can be fabricated(FIG. 1A2).

As shown in FIGS. 1A1 and 1A2, the shape difference between the glasslayer 104 a resulted by the pre-baking on the glass frit and the glasslayer 105 a resulted by the irradiation with the laser light to bewelded to the counter substrate is small in the sealed structure of oneembodiment of the present invention. That is, the shape of the glasslayer is less likely to be changed on attachment between the substrateand the counter substrate. Thus, such attachment of the pair ofsubstrates with glass enables suppression of spreading of the adhesiveout of its predetermined region upon the attachment. Accordingly, withone embodiment of the present invention, a slim border of the sealedstructure can be achieved. Further, glass can be prevented from mixinginto the region for an object to be sealed, thereby suppressingcontamination of the object.

Further, the glass layer is less likely to be deformed on attachment,and thus the shape of the glass layer after attachment can be predictedbefore the attachment, which enables suppression of generation of such adefect that the glass layer does not exist in its predetermined regionafter the attachment and thus an object to be sealed cannot be sealedenough. Accordingly, a sealed structure which has high sealingcapability and whose border can be slim can be manufactured at highyield.

Further, for example, a defect portion where the glass layer 104 a doesnot exist in its region can be detected; thus, the substrate 101 havingthis defect portion can be removed from the manufacturing process,thereby reducing execution of an unnecessary manufacturing process;alternatively, frit paste may be further applied over that substrate101, and pre-baking may be performed thereon again, whereby the defectportion can be repaired. In this manner, according to one embodiment ofthe present invention, a reduction in yield can be suppressed bydetecting a defect portion before attachment.

Next, sealed structures of comparison examples are described using FIGS.1B1 and 1B2, and FIGS. 1C1 and 1C2. In this embodiment, sealedstructures in each of which a substrate 101 and a counter substrate areattached to each other with resin are given as the comparison examples.

Plan views of the substrates 101 in a state just before being attachedto the counter substrate are shown in FIG. 1B1 and 1C1. Plan views ofsealed structures of comparison examples are shown in FIGS. 1B2 and 1C2.

A resin layer 204 a is provided over the substrate 101 which isquadrangular as shown in FIG. 1B1 such that its inner contour is alongthe periphery of a region for an object to be sealed 102 a.

In the sealed structure of the comparison example shown in FIG. 1B2, aresin layer 205 a is provided over the substrate 101 so as to surround aregion for an object to be sealed 102 b. The substrate 101 is attachedto the counter substrate (not shown) with the resin layer 205 a. Theregion for an object to be sealed 102 b is positioned in a spacesurrounded by the pair of substrates and the resin layer 205 a.

Upon the attachment between the substrate 101 and the counter substrate,the shape of the resin layer 204 a sandwiched therebetween is changedto, for example, increase its width by crush. Therefore, the widthbetween the inner contour and the outer contour of the resin layer 205 ain the sealed structure shown in FIG. 1B2 is larger than that betweenthe inner contour and the outer contour of the resin layer 204 a overthe substrate 101 shown in FIG. 1B1. Further, the area of the region foran object to be sealed 102 b is smaller than that of the region for anobject to be sealed 102 a; a slim border is not achieved.

As described above, resin is more likely to spread out of itspredetermined region on attachment of the pair of the substrates.Consequently, the area of the region for an object to be sealed becomessmall, and it is difficult to achieve a slim border. Further, the objectmay be contaminated by mixing of the resin into the region for an objectto be sealed, which is not preferable.

A resin layer 204 b is provided over the substrate 101 which isquadrangular as shown in FIG. 1C1 such that its inner contour is alongthe periphery of a region for an object to be sealed 102 a.

In the sealed structure of the comparison example shown in FIG. 1C2, aresin layer 205 b is provided over the substrate 101 so as to surroundthe region for an object to be sealed 102 a. The substrate 101 isattached to the counter substrate (not shown) with the resin layer 205b.

The application quantity of the resin layer 204 b in FIG. 1C1 is smallerthan that of the resin layer 204 a in FIG. 1B1. Consequently, the areaof the region for an object to be sealed 102 a is not changed even bycrushing the resin with the pair of substrates on attachment in thesealed structure of the comparison example shown in FIG. 1C2. However,there is a portion surrounded by a dotted line 11, where the resin doesnot exist. If the resin does not exist in its predetermined region, anobject cannot be sufficiently sealed by the sealed structure.

As described above, too much reduction in application quantity of theresin in order to suppress the spread out of its appropriate region maylead to a lack of sufficient resin in its region after the attachment,resulting in a lack of sealing capability of the sealed structure.

Therefore, achieving of both of a slim border and high sealingcapability is difficult in the sealed structure using resin.

On the other hand, the sealed structure of one embodiment of the presentinvention uses the glass layer for attaching the pair of substrates.Such attachment of the pair of substrates with the glass enables moresuppression of spreading of the adhesive out of its predetermined regionthan the case of using resin. Accordingly, a slim border of the sealedstructure can be achieved.

Further, the glass layer is less likely to be deformed on attachment,and thus the shape of the glass layer after attachment can be predictedbefore the attachment, which enables suppression of generation of such adefect that the glass layer does not exist in its predetermined regionafter the attachment and thus an object to be sealed cannot be sealedenough. Accordingly, a sealed structure which has high sealingcapability and whose border can be slim can be manufactured at highyield.

A plan view of a sealed structure of another embodiment of the presentinvention is shown in FIG. 2A.

In a sealed structure of one embodiment of the present invention shownin FIG. 2A, a glass layer 105 b is provided over a substrate 101 suchthat its inner contour is along the periphery of a region for an objectto be sealed 102 c. The substrate 101 is attached to a counter substrate(not shown) with the glass layer 105 b. The region for an object to besealed 102 c is positioned in a space surrounded by the pair ofsubstrates and the glass layer 105 b.

In the glass layer 105 b, the width of a corner portion is smaller thanthat of a side portion. A beam diameter of laser light selected inaccordance with the width of the side portion allows the glass layer 105b and the counter substrate to be surely welded to each other even inthe corner portion (there occurs almost no portion of the glass layer105 b which is not welded to the counter substrate). Therefore, theglass layer 105 b and the counter substrate can be welded to each othermore surely while suppressing damage of the laser light on an object tobe sealed, than in the case where the width of the corner portion islarger than that of the side portion. Accordingly, a sealed structurewith high sealing capability can be provided.

As shown in the glass layer 105 b shown in FIG. 2A, the inner contour inthe corner portion of the glass layer may have an angle. In the casewhere the inner contour has an angle, the angle is any of a right angle,an acute angle, and an obtuse angle.

An enlarged view of a portion surrounded by a dotted line 12 in FIG. 2Ais shown in FIG. 2B. For forming the glass layer 105 b whose innercontour has an angle shown in FIG. 2A, a structure having an angle 150as shown in FIG. 2B may be formed over the substrate 101 to shape theglass layer 105 b (glass frit or frit paste for forming the glass layer105 b). For example, the structure 150 can be provided in the region foran object to be sealed 102 c. In the case where the structure 150 isprovided in the region for an object to be sealed 102 c, the structure150 is preferably removed after the glass layer is shaped, because thearea of the region for an object to be sealed 102 c cannot be decreasedand thus a slim border is achieved. The structure 150 may also beprovided outside the region for forming the glass layer. In the case ofusing a low-viscosity frit paste, the frit paste may be less likely tokeep its shape due to surface tension or the like; in that case, such astructure is preferably provided over the substrate regardless of theshape of the glass layer, which enables the frit paste to be formedeasily into an appropriate shape.

Further, in order to obtain the glass layer (or glass frit or fritpaste) with an appropriate shape, an application step or a pre-bakingstep of the frit paste may be divided into several times. For example,as shown in FIG. 2C, the application step and the pre-baking step of thefrit paste can be performed separately in a side portion 214 a and acorner portion 214 b. Specifically, first, frit paste is applied to aregion for the side portion 214 a, and pre-baking is performed thereon;then, frit paste is applied to a region for the corner portion 214 b,and pre-baking is performed thereon.

Alternatively, as shown in FIG. 2D, an application step and a pre-bakingstep of the frit paste can be performed separately in one pair of facingside portions 224 a and the other pair of facing side portions 224 b.Specifically, first, frit paste is applied to regions for the one pairof facing side portions 224 a, and pre-baking is performed thereon;then, frit paste is applied to regions for the other pair of facing sideportions 224 b, and pre-baking is performed thereon.

A part of a method for manufacturing a sealed structure of oneembodiment of the present invention is described using FIGS. 10A to 10C.

A plan view of the substrate 101 just before the attachment to thecounter substrate is shown in FIG. 10A.

A glass layer 104 a is provided over a substrate 101 which isquadrangular as shown in FIG. 10A such that its inner contour is alongthe periphery of a region for an object to be sealed 102 a.

FIGS. 10B and 10C are cross-sectional views taken along chain line X-Yin FIG. 10A.

First, a masking tape 106 is provided in the region for an object to besealed 102 a over the substrate 101. The masking tape 106 is notnecessarily in contact with the substrate 101. For example, the maskingtape 106 may be provided to cover an object to be sealed whose heatresistance is high (enough to withstand at least pre-baking and the likeperformed later), which is provided over the substrate 101.

Next, frit paste 103 a is applied along the side surface of the maskingtape 106 (FIG. 10B).

Then, the frit paste 103 a is dried to lose its fluidity and becomesolid to keep its shape, and then, the masking tape 106 is removed fromthe substrate 101.

After that, pre-baking is performed on the frit paste 103 a, so that theglass layer 104 a is formed (FIG. 10C).

In the sealed structure fabricated through the above process, the glasslayer is provided such that its inner contour is along the periphery ofthe region for an object to be sealed 102 a. Spreading of the adhesiveout of its appropriate region upon attachment can be more suppressed byusing the glass for attaching the pair of substrates than in the case ofusing resin. Accordingly, a slim border of the sealed structure can beachieved.

Further, the pair of substrates is attached to each other with the glasslayer in the sealed structure fabricated through the above process.Further, the sealing capability of glass is higher than that of resin,and thus glass is preferable. In addition, glass is less likely to bedeformed on attachment, and thus the shape of the glass layer afterattachment can be predicted before the attachment, which enablessuppression of generation of such a defect that the glass layer does notexist in its predetermined region after the attachment and thus anobject to be sealed cannot be sealed enough. Accordingly, a sealedstructure with high sealing capability can be manufactured at highyield.

Further, the frit paste 103 a can be provided over the substrate, in itsdesired shape after attachment, which leads to simplification ofmanufacturing of the sealed structure.

FIG. 2E is a plan view of a sealed structure of another embodiment ofthe present invention. The shape of a substrate of the sealed structureof one embodiment of the present invention is not limited to quadranglein the plan view. For example, as shown in FIG. 2E, a substrate theshape of which is hexagonal in the plan view can be used in oneembodiment of the present invention.

In a sealed structure shown in FIG. 2E, a glass layer 135 is providedover a substrate 131 the shape of which is hexagonal, such that itsinner contour is along the periphery of a region for an object to besealed 132. Then, the substrate 131 is attached to a counter substratewith the glass layer 135, so that the region for an object to be sealed132 surrounded by the pair of substrates and the glass layer 135 isprovided.

In the glass layer 135, the width of a corner portion is smaller thanthat of a side portion. A beam diameter of laser light selected inaccordance with the width of the side portion allows the glass layer 135and the counter substrate to be surely welded to each other even in thecorner portion (there occurs almost no portion of the glass layer 135which is not welded to the counter substrate). Therefore, the glasslayer 135 and the counter substrate can be welded to each other moresurely while suppressing damage of the laser light on an object to besealed, than in the case where the width of the corner portion is largerthan that of the side portion. Accordingly, a sealed structure with highsealing capability can be provided.

Accordingly, application of one embodiment of the present invention canprovide a sealed structure achieving both of high sealing capability anda slim border, in which damage of laser light on an object sealed by thesealed structure is suppressed to be provided.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 2

In this embodiment, a light-emitting device of one embodiment of thepresent invention is described using FIGS. 3A to 3C.

FIG. 3A is a plan view of a light-emitting device of one embodiment ofthe present invention. FIG. 3B is a cross-sectional view taken alongchain line A-B FIG. 3A.

The light-emitting device shown in FIGS. 3A and 3B includes alight-emitting portion 802 provided in a space 810 surrounded by asupport substrate 801, a sealing substrate 806, and a glass layer 805.

The glass layer 805 is provided such that its inner contour is along theperiphery of a region for an object to be sealed (here, thelight-emitting portion 802).

In particular, as for the glass layer 805, the width of a corner portionis smaller than that of a side portion.

The light-emitting portion 802 includes a light-emitting element 130(including a first electrode 118, an EL layer 120, and a secondelectrode 122). A bank 124 covers an end portion of the first electrode118, and is provided with an opening which corresponds to alight-emitting region of the light-emitting element 130.

In the above-described light-emitting device, the pair of substrates isattached to each other with the glass layer 805. Since the sealingcapability of glass is high, degradation of the light-emitting element130 due to moisture, oxygen, or the like can be suppressed, so that thereliability of the light-emitting device is high. Further, since theinner contour of the glass layer 805 is along the periphery of theobject to be sealed, a slim border of the light-emitting device can beachieved.

Further, the attachment of the pair of substrates with the glass enablesmore suppression of spreading of the adhesive out of its predeterminedregion than the case of using resin. Accordingly, a slim border of thelight-emitting device can be achieved.

Further, the glass layer is less likely to be deformed on attachment,and thus the shape of the glass layer 805 after attachment can bepredicted before the attachment, which enables suppression of generationof such a defect that the glass layer 805 does not exist in itspredetermined region after the attachment and thus an object to besealed cannot be sealed enough. Accordingly, a light-emitting devicewhich has high reliability and whose border can be slim can bemanufactured at high yield.

Further, the glass layer 805 (or glass frit, frit paste, or the like forforming the glass layer 805) can be provided over the substrate, in itsdesired shape after attachment, which leads to simplification ofmanufacturing of the light-emitting device.

Further, in the glass layer 805, the width of the corner portion issmaller than that of the side portion. A beam diameter of laser lightselected in accordance with the width of the side portion allows theglass layer 805 and the counter substrate to be surely welded to eachother even in the corner portion (there occurs almost no portion of theglass layer 805 which is not welded to the counter substrate).Therefore, the glass layer 805 and the counter substrate can be weldedto each other more surely while suppressing damage of the laser light onan object to be sealed, than in the case where the width of the cornerportion is larger than that of the side portion. Accordingly, alight-emitting device achieving both of high sealing capability and aslim border, in which damage of laser light on the light-emittingelement 130 is suppressed to be provided.

Further, the light-emitting element 130 is provided over the supportsubstrate 801 in the light-emitting device described in this embodimentand there is a case where the light-emitting element 130 contains amaterial whose heat resistance is low. Therefore, also for suppressingdeterioration of such an element in the step of pre-baking of frit pasteor the like, it is preferable that the glass layer 805 be formed overthe sealing substrate 806 in its forming process.

The support substrate 801 and the sealing substrate 806 are in directcontact with the glass layer 805 in this embodiment. However,embodiments of the present invention are not limited thereto; one orboth of the substrates may be in indirect contact with the glass layer805 through a film provided therebetween. Since irradiation with laserlight is performed in the manufacturing process, the film providedbetween the substrate and the glass layer 805 is preferably formed usinga high heat-resistant material. For example, an inorganic insulatingfilm formed as a base film or an interlayer insulating film over thesubstrate may be in direct contact with the glass layer 805.

In the light-emitting device shown in FIG. 3A, there is a space in acorner portion of the sealing substrate 806 outside the glass layer 805.As shown in FIG. 3C, in such a portion which is in the corner portion ofthe sealing substrate 806 outside the glass layer 805, a resin layer 815with which the support substrate 801 is attached to the sealingsubstrate 806 may be provided. In fabricating or using a light-emittingdevice, force is likely to be more applied to a corner portion of thelight-emitting device, and thus a pair of attached substrates of thelight-emitting device tends to be detached from each other from thecorner portion. Resin, which is highly impact resistant and is lesslikely to be broken by deformation by external force or the like,enables such a detachment of the pair of attached substrates from eachother by force concentrated on the corner portion of the light-emittingdevice to be suppressed. Therefore, providing the resin layer 815 in thecorner portion where the pair of substrate is attached outside the glasslayer 805 leads to achievement of a highly reliable light-emittingdevice.

Materials that can be Used for Light-Emitting Device of One Embodimentof the Present Invention

Examples of materials that can be used for the light-emitting device ofone embodiment of the present invention are described below. As to theglass layer, refer to the above-described description.

[Support Substrate 801, Sealing Substrate 806]

As materials for the substrates, glass, quartz, an organic resin, or thelike can be used. Specifically, a material which has a heat resistancewhich is high to withstand the process temperature in the manufacturingprocess of the sealed structure, such as pre-baking or laser lightirradiation is used. For the substrate on the side from which light fromthe light-emitting element is extracted, a material which transmits thatlight is used.

In order to suppress dispersion of an impurity included in the supportsubstrate 801 into any element provided over the support substrate 801,to provide an insulating layer on the top surface of the supportsubstrate 801 or to perform a heat treatment on the support substrate801 is preferable.

[Light-Emitting Element 130]

There is no limitation on the method for driving the light-emittingelement 130; either an active matrix method or a passive matrix methodcan be used. Further, any of a top emission structure, a bottom emissionstructure, and a dual emission structure can be used.

A light-emitting element with a bottom emission structure is used as anexample for description in this embodiment.

As examples of a light-transmitting material for the first electrode118, indium oxide, indium tin oxide (ITO), indium zinc oxide, zincoxide, zinc oxide to which gallium is added, and the like can be given.

Further, for the first electrode 118, a metal material such as gold,platinum, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper,palladium, or titanium can also be used. A nitride of the metal material(e.g., titanium nitride) or the like may also be used. Graphene or thelike may also be used. In the case of using the metal material (or thenitride thereof), the first electrode is preferably formed to be thin soas to be able to transmit light.

The EL layer 120 includes at least a light-emitting layer. Thelight-emitting layer contains a light-emitting organic compound. The ELlayer 120 can have a stacked-layer structure in which a layer containinga substance having a high electron-transport property, a layercontaining a substance having a high hole-transport property, a layercontaining a substance having a high electron-injection property, alayer containing a substance having a high hole-injection property, alayer containing a bipolar substance (a substance having a highelectron-transport property and a high hole-transport property), and thelike are combined as appropriate to the above-described light-emittinglayer. Examples of the structure of the EL layer are described in detailin Embodiment 5.

The second electrode 122 is provided on the side opposite to the lightextraction side and is formed using a reflective material. As thereflective material, a metal material such as aluminum, gold, platinum,silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, orpalladium can be used. Any of the following can also be used: an alloycontaining aluminum (aluminum alloy) such as an alloy of aluminum andtitanium, an alloy of aluminum and nickel, and an alloy of aluminum andneodymium; and an alloy containing silver such as an alloy of silver andcopper. The alloy of silver and copper is preferable because of its highheat resistance. Lanthanum, neodymium, or germanium, or the like may beadded to the metal material or alloy.

[Bank 124]

As a material for the bank 124, an organic resin or an inorganicinsulating material can be used. As the organic resin, for example, apolyimide resin, a polyamide resin, an acrylic resin, a siloxane resin,an epoxy resin, or a phenol resin can be used.

In particular, either a negative photosensitive resin or a positivephotosensitive resin is preferably used for easy formation of the bank124.

The bank 124 is provided so as to cover an end portion of the firstelectrode 118. The bank 124 is preferably formed to have a curvedsurface with curvature in its upper end portion or lower end portion inorder to improve the coverage with the EL layer 120 or the secondelectrode 122 which is formed over the bank 124.

There is no particular limitation to the method for forming the bank; aphotolithography method, a sputtering method, an evaporation method, adroplet discharging method (e.g., an inkjet method), a printing method(e.g., a screen printing method or an off-set printing method), or thelike may be used.

[Space 810]

The space 810 may be filled with an inert gas such as a rare gas or anitrogen gas or a solid such as an organic resin, or may be in a reducedpressure atmosphere. A dry agent may be provided in the space 810. Forthe dry agent, a substance which absorbs moisture and the like bychemical adsorption or a substance which adsorbs moisture and the likeby physical adsorption can be used. An oxide of an alkali metal, anoxide of an alkaline earth metal (e.g., calcium oxide or barium oxide),sulfate, a metal halide, perchlorate, zeolite, and silica gel can begiven as examples thereof.

[Resin Layer 815]

The resin layer 815 can be formed using a known material including aphotocurable resin such as an ultraviolet curable resin, a thermosettingresin, or the like; in particular, a material which does not transmitmoisture or oxygen is preferably used.

In particular, a photocurable resin is preferably used. The organic ELelement contains a material having low heat resistance in some cases. Aphotocurable resin, which is cured by light irradiation, is preferablyused because change in its film quality and deterioration of an organicEL material itself caused by heating of the organic EL element can besuppressed.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 3

In this embodiment, a light-emitting device of one embodiment of thepresent invention is described using FIGS. 4A and 4B. FIG. 4A is a planview of a light-emitting device of one embodiment of the presentinvention. FIG. 4B is a cross-sectional view taken along chain line C-DFIG. 4A.

In a light-emitting device of this embodiment, a support substrate 801is attached to a sealing substrate 806 with a glass layer 805.

The glass layer 805 is provided such that its inner contour is along theperiphery of an object to be sealed.

In particular, as for the glass layer 805, the width of a corner portionis smaller than that of a side portion. Further, in the corner portionof the glass layer 805, the inner contour has an angle, specifically, anobtuse angle.

In the light-emitting device of this embodiment, a light-emittingelement 130 (a first electrode 118, an EL layer 120, and a secondelectrode 122) is provided in a space 810 surrounded by the supportsubstrate 801, the sealing substrate 806, and the glass layer 805. Thelight-emitting element 130 has a bottom emission structure;specifically, the first electrode 118 is provided over the supportsubstrate 801, the EL layer 120 is provided over the first electrode118, and the second electrode 122 is provided over the EL layer 120.

In the above-described light-emitting device, the pair of substrates isattached to each other with the glass layer 805. Since the sealingcapability of glass is high, degradation of the light-emitting element130 due to moisture, oxygen, or the like can be suppressed, so that thereliability of the light-emitting device is high. Further, since theinner contour of the glass layer 805 is along the periphery of theobject to be sealed, a slim border of the light-emitting device can beachieved.

Further, the attachment of the pair of substrates with the glass enablesmore suppression of spreading of the adhesive out of its predeterminedregion than the case of using resin. Accordingly, a slim border of thelight-emitting device can be achieved.

Further, the glass layer 805 is less likely to be deformed onattachment, and thus the shape of the glass layer 805 after attachmentcan be predicted before the attachment, which enables suppression ofgeneration of such a defect that the glass layer 805 does not exist inits predetermined region after the attachment and thus an object to besealed cannot be sealed enough. Accordingly, a light-emitting devicewhich has high reliability and whose border can be slim can bemanufactured at high yield.

Further, the glass layer 805 (or glass frit, frit paste, or the like forforming the glass layer 805) can be provided over the substrate, in itsdesired shape after attachment, which leads to simplification ofmanufacturing of the light-emitting device.

Further, in the glass layer 805, the width of the corner portion issmaller than that of the side portion. A beam diameter of laser lightselected in accordance with the width of the side portion allows theglass layer 805 and the counter substrate to be surely welded to eachother even in the corner portion (there occurs almost no portion of theglass layer 805 which is not welded to the counter substrate).Therefore, the glass layer 805 and the counter substrate can be weldedto each other more surely while suppressing damage of the laser light onan object to be sealed, than in the case where the width of the cornerportion is larger than that of the side portion. Accordingly, alight-emitting device achieving both of high sealing capability and aslim border, in which damage of laser light on the light-emittingelement 130 is suppressed to be provided.

A first terminal 809 a is electrically connected to an auxiliary wiring163 and the first electrode 118. An insulating layer 125 is provided ina region which overlaps with the auxiliary wiring 163 over the firstelectrode 118. The first terminal 809 a is electrically isolated fromthe second electrode 122 by the insulating layer 125. A second terminal809 b is electrically connected to the second electrode 122. In thisembodiment, the first electrode 118 is formed over the auxiliary wiring163; however, the auxiliary wiring 163 may be formed over the firstelectrode 118.

The organic EL element emits light in a region with a refractive indexhigher than that of the air; thus, when light is extracted to the air,total reflection occurs in the organic EL element or at the interfacebetween the organic EL element and the air under a certain condition,which results in a light extraction efficiency of lower than 100%.

Specifically, supposing that the refractive index of a medium A ishigher than the refractive index of a medium B and the refractive indexof the medium B is lower than the refractive index of the EL layer, whenlight enters the medium B from the medium A, total reflection occurs insome cases depending on its incident angle.

In that case, it is preferable that an uneven surface structure beprovided at the interface between the medium A and the medium B. Withsuch a structure, such phenomenon that light entering the medium B fromthe medium A at an incidence angle exceeding a critical angle is totallyreflected and the wave of the light propagates inside the light-emittingdevice to lower the light extraction efficiency can be suppressed.

For example, an uneven surface structure 161 a is preferably provided inthe interface between the support substrate 801 and the air. Therefractive index of the support substrate 801 is higher than therefractive index of the air. Therefore, with the uneven surfacestructure 161 a provided in the interface between the air and thesupport substrate 801, light which cannot be extracted to the air owingto total reflection can be reduced, whereby the light extractionefficiency of the light-emitting device can be improved.

Further, an uneven surface structure 161 b is preferably provided in theinterface between the light-emitting element 130 and the supportsubstrate 801.

However, in the organic EL element, unevenness of the first electrode118 might lead to occurrence of leakage current in the EL layer 120formed over the first electrode 118. Therefore, in this embodiment, aplanarization layer 162 having a refractive index higher than or equalto that of the EL layer 120 is provided in contact with the unevensurface structure 161 b. Accordingly, the first electrode 118 can beprovided to be a flat film, and thus occurrence of leakage current inthe EL layer due to the unevenness of the first electrode 118 can besuppressed. Further, owing to the uneven surface structure 161 b in theinterface between the planarization layer 162 and the support substrate801, light which cannot be extracted to the air due to total reflectioncan be reduced, whereby the light extraction efficiency of thelight-emitting device can be increased.

In FIG. 4B, the support substrate 801, the uneven surface structure 161a, and the uneven surface structure 161 b are different components;however, embodiments of the present invention are not limited thereto.Two or all of these may be formed as one component.

Although the light-emitting device shown in FIG. 4A is octagonal,embodiments of the present invention are not limited thereto. The shapeof the light-emitting device may be any other polygonal or a shapehaving a curved portion. As the shape of the light-emitting device, atriangle, a quadrangle, a hexagon, or the like is particularlypreferable. The reason for this is that a plurality of light-emittingdevices can be provided with a redundant space as little as possible ina limited area; a light-emitting device can be formed using a limitedsubstrate area efficiently. Further, the number of light-emittingelements in the light-emitting device is not limited to one; a pluralityof light-emitting elements may be provided therein.

Materials that can be Used for Light-Emitting Device of One Embodimentof the Present Invention

Examples of materials that can be used for the light-emitting device ofone embodiment of the present invention are described below. As for thesubstrate, the light-emitting element, the sealant, and the space, theirrespective materials described above in the embodiments can be used.

[Insulating Layer 125]

The insulating layer 125 can be formed using a material similar to anyof the materials for the bank 124 described above in the embodiments.

[Auxiliary Wiring 163, First Terminal 809 a, and Second Terminal 809 b]

The auxiliary wiring 163, the first terminal 809 a, and the secondterminal 809 b are preferably formed by the same step(s) (at the sametime), because the number of manufacturing steps of the light-emittingdevice can be reduced. For example, they can be formed to have asingle-layer structure or a stacked-layered structure using a materialselected from copper (Cu), titanium (Ti), tantalum (Ta), tungsten (W),molybdenum (Mo), chromium (Cr), neodymium (Nd), scandium (Sc), andnickel (Ni) or an alloy material containing any of these materials asits main component.

[Uneven Surface Structure 161 a, 161 b]

The shape of the unevenness does not necessarily have an order ofregularity. When the shape of the unevenness is periodic, the unevennessfunctions as a diffraction grating depending on the size of theunevenness, so that an interference effect is increased and light with acertain wavelength is more likely to be extracted to the air. Therefore,it is preferable that the shape of the unevenness be not periodic.

There is no particular limitation on the shape of bottom surface of theunevenness; for example, the shape may be a polygon such a triangle or aquadrangle, a circle, or the like. When the shape of bottom surface ofthe unevenness has an order of regularity, the unevenness is preferableso that gaps are not formed between adjacent portions of the unevenness.A regular hexagon is given as an example of a preferable shape of thebottom surface.

There is no particular limitation on the cross-sectional shape of bottomsurface of the unevenness in the direction perpendicular to the bottomsurface; for example, a hemisphere or a shape with a vertex such as acircular cone, a pyramid (e.g., a triangular pyramid or a squarepyramid), or an umbrella shape can be used.

In particular, the size or the height of the unevenness is preferably 1μm or more, because influence of interference of light can besuppressed.

The uneven surface structure 161 a, 161 b can be provided directlyon/underneath the support substrate 801. As the method therefor, forexample, an etching method, a sand blasting method, a microblastprocessing method, a droplet discharge method, a printing method (screenprinting or offset printing by which a pattern is formed), a coatingmethod such as a spin coating method, a dipping method, a dispensermethod, an imprint method, a nanoimprint method, or the like can be usedas appropriate.

As the material of the uneven surface structure 161 a, 161 b, forexample, resin can be used; specifically, a polyester resin such aspolyethylene terephthalate (PET) or polyethylene naphthalate (PEN), apolyacrylonitrile resin, a polyimide resin, an acrylic(polymethylmethacrylate) resin, a polycarbonate (PC) resin, apolyethersulfone (PES) resin, a polyamide resin, a cyclic olefin-basedresin, a cycloolefin resin, a polystyrene resin, a polyamide imideresin, a polyvinylchloride resin, or the like can be used. A resin inwhich two or more kinds of the above resins are combined may be used. Itis preferable to use an acrylic resin because of its high visible lighttransmittance. A cyclic olefin-based resin and a cycloolefin resin areeach preferable because they have high visible light transmittance andhigh heat resistance.

For the uneven surface structure 161 a, 161 b, a hemispherical lens, amicro lens array, a film provided with an uneven surface structure, alight diffusing film, or the like can be used. For example, the lens orfilm can be attached over/under the support substrate 801 with anadhesive or the like with substantially the same refractive index as thelens or film, so that the uneven surface structure 161 a, 161 b can beformed.

[Planarization Layer 162]

The planarization layer 162 is more flat in its one surface which is incontact with the first electrode 118 than in its other surface which isin contact with the uneven surface structure 161 b. Therefore, the firstelectrode 118 can be formed to be flat. As a result, generation ofleakage current in the EL layer 120 due to unevenness of the firstelectrode 118 can be suppressed.

As a material of the planarization layer 162, liquid, resin, or the likehaving a high refractive index can be used. The planarization layer 162has a light-transmitting property. As examples of the resin having ahigh refractive index, resin containing bromine, resin containingsulfur, and the like are given; for example, a sulfur-containingpolyimide resin, an episulfide resin, a thiourethane resin, a brominatedaromatic resin, or the like can be used. Polyethylene terephthalate(PET), triacetyl cellulose (TAC), or the like can also be used. As theliquid having high refractive index, contact liquid (refractive liquid)containing sulfur and methylene iodide, or the like can be used. Any ofa variety of methods suitable for the material may be employed forforming the planarization layer 162. For example, the above resin isdeposited by a spin coating method and is cured by heat or light. Thematerial and the formation method can be selected as appropriate inconsideration of the adhesion strength, ease of processing, or the like.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 4

In this embodiment, a light-emitting device of one embodiment of thepresent invention is described using FIGS. 5A and 5B. FIG. 5A is a planview of a light-emitting device of one embodiment of the presentinvention and FIG. 5B is a cross-sectional view taken along chain lineE-F in FIG. 5A.

An active matrix light-emitting device according to this embodimentincludes, over a support substrate 801, a light-emitting portion 802, adriver circuit portion 803 (gate side driver circuit portion), a drivercircuit portion 804 (source side drive circuit portion), and a glasslayer 805. The light-emitting portion 802 and the driver circuitportions 803 and 804 are sealed in a space 810 formed by the supportsubstrate 801, a sealing substrate 806, and the glass layer 805.

The glass layer 805 is provided such that its inner contour is along theperiphery of a region for an object to be sealed (here, regioncontaining the light-emitting portion 802 and the driver circuitportions 803 and 804)

In particular, as for the glass layer 805, the width of a corner portionis smaller than that of a side portion.

The light-emitting portion 802 shown in FIG. 5B includes a plurality oflight-emitting units each including a switching transistor 140 a, acurrent control transistor 140 b, and a second electrode 122electrically connected to a wiring (a source electrode or a drainelectrode) of the transistor 140 b.

A light-emitting element 130 has a top emission structure, including afirst electrode 118, an EL layer 120, and the second electrode 122.Further, a bank 124 is formed to cover an end portion of the secondelectrode 122.

The sealing capability of the above-described light-emitting device ishigh because the pair of substrates is attached to each other with theglass layer 805. Further, a slim border of the light-emitting device canbe achieved because the glass layer 805 is provided such that its innercontour is along the periphery of the object to be sealed. Further, theglass is less likely to be deformed on attachment, and thus the shape ofthe glass layer after attachment can be predicted before the attachment,which enables a light-emitting device which has high sealing capabilityand whose border can be slim to be manufactured at high yield. Further,the glass layer (or glass frit, frit paste, or the like for forming theglass layer) can be provided over the substrate, in its desired shapeafter attachment, which leads to simplification of manufacturing of thelight-emitting device.

Further, in the glass layer 805, the width of the corner portion issmaller than that of the side portion. A beam diameter of laser lightselected in accordance with the width of the side portion allows theglass layer 805 and the counter substrate to be surely welded to eachother even in the corner portion (there occurs almost no portion of theglass layer 805 which is not welded to the counter substrate).Therefore, the glass layer 805 and the counter substrate can be weldedto each other more surely while suppressing damage of the laser light onan object to be sealed, than in the case where the width of the cornerportion is larger than that of the side portion. Accordingly, alight-emitting device achieving both of high sealing capability and aslim border, in which damage of laser light on the light-emittingelement 130 is suppressed to be provided.

Over the support substrate 801, a lead wiring 809 for connecting anexternal input terminal through which a signal (e.g., a video signal, aclock signal, a start signal, or a reset signal) or a potential from theoutside is transmitted to the driver circuit portion 803, 804 isprovided. Here, an example thereof is described in which a flexibleprinted circuit (FPC) 808 is provided as the external input terminal. Aprinted wiring board (PWB) may be attached to the FPC 808. In thisspecification, the light-emitting device includes in its category notonly the light-emitting device itself but also the light-emitting deviceprovided with an FPC or a PWB.

The driver circuit portion 803, 804 includes a plurality of transistors.An example in which the driver circuit portion 803 includes a CMOScircuit which is a combination of an n-channel transistor 142 and ap-channel transistor 143 is shown in FIG. 5B. A circuit included in thedriver circuit portion can be formed using any type of circuit such as aCMOS circuit, a PMOS circuit, or an NMOS circuit. In this embodiment, adriver-integrated type in which a driver circuit and a light-emittingportion are formed over the same substrate is described; however,embodiments of the present invention are not limited to this structure,in which a driver circuit can be formed over a substrate that isdifferent from a substrate over which a light-emitting portion isformed.

To prevent increase in the number of manufacturing steps, the leadwiring 809 is preferably formed using the same material and the samestep(s) as those of the electrode or the wiring in the light-emittingportion or the driver circuit portion.

Described in this embodiment is an example in which the lead wiring 809is formed using the same material and the same step(s) as those of thegate electrode of the transistor included in the light-emitting portion802 and the driver circuit portion 803.

In FIG. 5B, the glass layer 805 is in contact with a first insulatinglayer 114 over the lead wiring 809. The adhesion of the glass layer 805to metal is low in some cases. Therefore, the glass layer 805 ispreferably in contact with an inorganic insulating film over the leadwiring 809; such a structure enables a light-emitting device with highsealing capability and high reliability to be achieved. As examples ofthe inorganic insulating film, an oxide film of a metal or asemiconductor, a nitride film of a metal or a semiconductor, and anoxynitride film of a metal or a semiconductor are given; specifically, asilicon oxide film, a silicon nitride film, a silicon oxynitride film, asilicon nitride oxide film, an aluminum oxide film, a titanium oxidefilm, and the like can be given.

Materials that can be Used for Light-Emitting Device of One Embodimentof the Present Invention

Examples of materials that can be used for the light-emitting device ofone embodiment of the present invention are described below. As for thesubstrate, the light-emitting element, the glass layer, the space, andthe bank, their respective materials described above in the embodimentscan be used.

[Transistor]

There is no particular limitation on the structure of the transistor(e.g., the transistor 140 a, 140 b, 142, or 143) used in thelight-emitting device of one embodiment of the present invention. Atop-gate transistor may be used, or a bottom-gate transistor such as aninverted staggered transistor may be used. A channel-etched type or achannel-stop (channel-protective) type may also be employed. Inaddition, there is no particular limitation on materials for thetransistor.

The gate electrode can be formed to have a single-layer structure or astacked-layer structure using any of metal materials such as molybdenum,titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, andscandium, or an alloy material which contains any of these elements, forexample. A structure may be employed in which a film of ahigh-melting-point metal such as titanium, molybdenum, or tungsten, or anitride film of any of these metals (a titanium nitride film, amolybdenum nitride film, or a tungsten nitride film) is stacked eitheror both of over and under a metal film of aluminum, copper, or the like.For example, a three layer structure consisting of a titanium film, analuminum film or a copper film, and a titanium film is preferablyemployed.

The gate insulating layer is formed using a material which transmitslight from the light-emitting element. The gate insulating layer can beformed to have a single-layer structure or a stacked-layer structureusing any of silicon oxide, silicon nitride, silicon oxynitride, siliconnitride oxide, and aluminum oxide by a plasma-enhanced CVD method, asputtering method, or the like, for example.

The semiconductor layer can be formed using a silicon semiconductor oran oxide semiconductor. As examples of the silicon semiconductor, singlecrystal silicon, polycrystalline silicon, and the like can be given. Asthe oxide semiconductor, an In-Ga-Zn-O-based metal oxide or the like canbe used as appropriate. The semiconductor layer is preferably formedusing an In-Ga-Zn-O-based metal oxide that is an oxide semiconductorsuch that the semiconductor layer is a semiconductor layer whoseoff-state current is small, because the off-state leakage current of thelight-emitting element 130 can be reduced.

As the source electrode layer and the drain electrode layer, forexample, a metal film containing an element selected from aluminum,chromium, copper, tantalum, titanium, molybdenum, and tungsten; a metalnitride film containing any of the above elements (e.g., a titaniumnitride film, a molybdenum nitride film, or a tungsten nitride film); orthe like can be used. A structure may also be used in which a film of ahigh-melting-point metal such as titanium, molybdenum, or tungsten, or anitride film of any of these metals (a titanium nitride film, amolybdenum nitride film, or a tungsten nitride film) is stacked eitheror both of over and under a metal film of aluminum, copper, or the like.For example, a three-layer structure consisting of a titanium film, analuminum film or a copper film, and a titanium film is preferably used.

Further or alternatively, the source electrode layer and the drainelectrode layer may be formed using a conductive metal oxide. As theconductive metal oxide, indium oxide (In₂O₃ or the like), tin oxide(SnO₂ or the like), zinc oxide (ZnO), ITO, indium oxide-zinc oxide(In₂O₃—ZnO or the like), or any of these metal oxide materials in whichsilicon oxide is contained can be used.

[First Insulating Layer 114, Second Insulating Layer 116]

The first insulating layer 114 and a second insulating layer 116 areformed using materials which transmit light from the light-emittingelement.

The first insulating layer 114 has an effect of preventing diffusion ofimpurities into the semiconductor included in the transistor. As thefirst insulating layer 114, an inorganic insulating film such as asilicon oxide film, a silicon oxynitride film, or an aluminum oxide filmcan be used.

As the second insulating layer 116, an insulating film with aplanarization function is preferably selected in order to reduce surfaceunevenness due to a color filter or the transistor. For example, anorganic material such as a polyimide resin, an acrylic resin, or abenzocyclobutene resin can be used. Other than such organic materials,it is also possible to use a low-dielectric constant material (a low-kmaterial) or the like. The second insulating layer 116 may be formed bystacking a plurality of insulating films formed using any of thesematerials.

[Color Filter 166, Black Matrix 164]

For the sealing substrate 806, a color filter 166 that is a coloringlayer is provided to overlap with (the light-emitting region of) thelight-emitting element 130. The color filter 166 is provided in order tocontrol the color of light emitted from the light-emitting element 130.For example, in a full-color display device using white light-emittingelements, a plurality of light-emitting units provided with colorfilters of different colors are used. In that case, three colors, red(R), green (G), and blue (B), may be used, or four colors, red (R),green (G), blue (B), and yellow (Y), may be used.

Further, a black matrix 164 is provided between the adjacent colorfilters 166 (not to overlap with the light-emitting region of thelight-emitting element 130). The black matrix 164 shields thelight-emitting unit from light emitted from the light-emitting element130 in its adjacent light-emitting unit and thereby prevents colormixture between the adjacent light-emitting units. Here, the colorfilter 166 is provided so that its end portion overlaps with the blackmatrix 164, whereby light leakage can be suppressed. The black matrix164 can be formed using a material which shields light emitted from thelight-emitting element 130, for example, metal or an organic resin. Theblack matrix 164 may be provided in a region other than thelight-emitting portion 802, such as the driver circuit portion 803.

Further, an overcoat layer 168 is formed to cover the color filter 166and the black matrix 164. The overcoat layer 168 is formed using amaterial which transmits light emitted from the light-emitting element130; for example, an inorganic insulating film or an organic insulatingfilm can be used. The overcoat layer 168 is not necessarily providedunless needed.

In this embodiment, a light-emitting device using a color filter methodis described as an example; however, embodiments of the presentinvention are not limited thereto. For example, a separate coloringmethod or a color conversion method may be used.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 5

In this embodiment, structural examples of an EL layer applicable to alight-emitting device of one embodiment of the present invention aredescribed using FIGS. 6A to 6C.

A known substance can be used for the EL layer; either a low molecularcompound or a high molecular compound can be used. The constituentsubstance of the EL layer is not limited to an organic compound; aninorganic compound may be contained.

In FIG. 6A, an EL layer 120 is provided between a first electrode 118and a second electrode 122. In the EL layer 120 in FIG. 6A, ahole-injection layer 701, a hole-transport layer 702, a light-emittinglayer 703, an electron-transport layer 704, and an electron-injectionlayer 705 are stacked in this order from the first electrode 118 side.

A plurality of EL layers may be stacked between the first electrode 118and the second electrode 122 as shown in FIG. 6B. In that case, a chargegeneration layer 709 is preferably provided between a first EL layer 120a and a second EL layer 120 b which are stacked. In a light-emittingelement having such a structure, problems such as energy transfer andquenching less occur, which enables expansion in the choice ofmaterials, thereby achieving a light-emitting element which has bothhigh light emission efficiency and long lifetime easily. Moreover,phosphorescence and fluorescence can be obtained easily from one ELlayer and the other EL layer, respectively. This structure can becombined with the above-described EL layer structure.

Further, by forming EL layers to emit light of different colors fromeach other, a light-emitting element can provide light emission of adesired color as a whole. For example, by forming a light-emittingelement having two EL layers such that the emission color of the firstEL layer and the emission color of the second EL layer are colorscomplementary to each other, the light-emitting element can providewhite light emission as a whole. The “colors complementary to eachother” means colors which become an achromatic color by mixture of them.That is, once respective light emitted from substances whose emissioncolors are complementary to each other is mixed together, white emissioncolor can be obtained. This applies to a light-emitting element havingthree or more EL layers.

As shown in FIG. 6C, the EL layer 120 may include the hole-injectionlayer 701, the hole-transport layer 702, the light-emitting layer 703,the electron-transport layer 704, an electron-injection buffer layer706, an electron-relay layer 707, and a composite material layer 708which is in contact with the second electrode 122, between the firstelectrode 118 and the second electrode 122.

It is preferable to provide the composite material layer 708 which is incontact with the second electrode 122, because damage on the EL layer120 particularly in formation of the second electrode 122 by asputtering method can be attenuated.

Further, by the electron-injection buffer layer 706, an injectionbarrier between the composite material layer 708 and theelectron-transport layer 704 can be reduced; thus, electrons generatedin the composite material layer 708 can be easily injected to theelectron-transport layer 704.

Furthermore, the electron-relay layer 707 is preferably formed betweenthe electron-injection buffer layer 706 and the composite material layer708. The electron-relay layer 707 is not necessarily provided; however,the electron-relay layer 707 having a high electron-transport propertyenables electrons to be rapidly transported to the electron-injectionbuffer layer 706.

The structure in which the electron-relay layer 707 is sandwichedbetween the composite material layer 708 and the electron-injectionbuffer layer 706 is a structure in which the acceptor substancecontained in the composite material layer 708 and the donor substancecontained in the electron-injection buffer layer 706 are less likely tointeract with each other, and thus their functions hardly interfere witheach other. Accordingly, an increase in drive voltage can be suppressed.

Examples of respective materials which can be used for the layers aredescribed below. Each layer is not limited to a single layer, but may bea stack of two or more layers.

<Hole-Injection Layer 701>

The hole-injection layer 701 is a layer containing a substance having ahigh hole-injection property.

As the substance having a high hole-injection property, for example, ametal oxide such as molybdenum oxide, vanadium oxide, ruthenium oxide,tungsten oxide, or manganese oxide, a phthalocyanine-based compound suchas phthalocyanine (H₂Pc) and copper(II) phthalocyanine (CuPc), or thelike can be used.

Further, a high molecular compound such as poly(N-vinylcarbazole)(abbreviation: PVK) or poly(4-vinyltriphenylamine) (abbreviation:PVTPA), or a high molecular compound to which acid is added, such aspoly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS)can also be used.

In particular, for the hole-injection layer 701, a composite materialcontaining an organic compound having a high hole-injection property andan electron acceptor (acceptor) is preferably used. Such a compositematerial has an excellent hole-injection and hole-transport propertiesbecause holes are generated in the organic compound by the electronacceptor. Such a composite material enables the hole-transportcapability from the first electrode to the EL layer to be increased,whereby the drive voltage of the light-emitting element can bedecreased.

Such a composite material can be formed by co-evaporation of an organiccompound having a high hole-transport property and an electron acceptor.The hole-injection layer 701 is not limited to a structure in which anorganic compound having a high hole-transport property and an electronacceptor are contained in the same film, but may be a structure in whicha layer containing an organic compound having a high hole-transportproperty and a layer containing an electron acceptor may be stacked.Specifically, a layer containing an electron acceptor is in contact withthe first electrode 118.

The organic compound used in the composite material is an organiccompound whose hole-transport property is higher than itselectron-transport property; particularly, it is preferable that thehole mobility of the organic compound be greater than or equal to 10⁻⁶cm²/Vs. As the organic compound for the composite material, any of avariety of compounds including an aromatic amine compound, a carbazolederivative, an aromatic hydrocarbon compound, and a high molecularcompound can be used.

As examples of the aromatic amine compound,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB orα-NPD), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation:BPAFLP), and the like can be given.

As examples of the carbazole derivative, 4,4′-di(N-carbazolyl)biphenyl(abbreviation: CBP), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole(abbreviation: CzPA),9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:PCzPA), and the like can be given.

As examples of the aromatic hydrocarbon compound,2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),9,10-diphenylanthracene (abbreviation: DPAnth), and the like can begiven.

As examples of the high molecular compound, PVK, PVTPA, and the like canbe given.

As examples of the electron acceptor for the composite material, atransition metal oxide or an oxide of a metal belonging to Group 4 toGroup 8 of the periodic table can be given. Specifically, molybdenumoxide is preferable. Molybdenum oxide is easy to handle because of itsstability in the air and its low hygroscopic property.

<Hole-Transport Layer 702>

The hole-transport layer 702 is a layer which contains a substancehaving a high hole-transport property.

The substance having a high hole-transport property is a substance whosehole-transport property is higher than its electron-transport property;particularly, it is preferable that the hole mobility of the substancehaving a high hole-transport property be greater than or equal to 10⁻⁶cm²/Vs. For example, any of a variety of compounds such as an aromaticamine compound such as NPB or BPAFLP, a carbazole derivative such asCBP, CzPA, or PCzPA, an aromatic hydrocarbon compound such as t-BuDNA,DNA, or DPAnth, and a high molecular compound such as PVK or PVTPA canbe used.

<Light-Emitting Layer 703>

For the light-emitting layer 703, a fluorescent compound that exhibitsfluorescence or a phosphorescent compound that exhibits phosphorescencecan be used.

As examples of the fluorescent compound for the light-emitting layer703,N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S),N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA), rubrene, and the like can be given.

As examples of the phosphorescent compound for the light-emitting layer703, metallo-organic complexes such asbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)picolinate(abbreviation: FIrpic), tris(2-phenylpyridinato-N,C^(2′))iridium(III)(abbreviation: Ir(ppy)₃), and(acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: Ir(mppr-Me)₂(acac)) can be given.

The light-emitting layer 703 may have a structure in which any of theabove-described light-emitting organic compounds (a light-emittingsubstance or a guest material) is dispersed in another substance (a hostmaterial). As the host material, any of a variety of materials can beused, and it is preferable to use a substance which has a lowestunoccupied molecular orbital level (LUMO level) higher than that of theguest material and has a highest occupied molecular orbital level (HOMOlevel) lower than that of the guest material.

With a structure in which a guest material is dispersed in a hostmaterial, crystallization of the light-emitting layer 703 can besuppressed. Further, concentration quenching due to high concentrationof the guest material can be suppressed.

As the host material, specifically, a metal complex such astris(8-quinolinolato)aluminum(III) (abbreviation: Alq) orbis(2-methyl-8-quinolinolato) (4-phenylphenolato)aluminum(III)(abbreviation: BAlq), a heterocyclic compound such as3-(4-butylphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ), bathophenanthroline (abbreviation: BPhen), orbathocuproine (abbreviation: BCP), a condensed aromatic compound such asCzPA, DNA, t-BuDNA, or DPAnth, an aromatic amine compound such as NPB,or the like can be used.

Plural kinds of materials can be used for the host material. Forexample, to suppress crystallization, a substance such as rubrene whichsuppresses crystallization, may be further added. In addition, NPB, Alq,or the like may be further added in order to efficiently transfer energyto the guest material.

Further, by providing a plurality of light-emitting layers such thattheir respective emission colors are different from each other, lightemission of a desired color can be obtained from the light-emittingelement as a whole. For example, by using first and secondlight-emitting layers whose emission colors are complementary to eachother in a light-emitting element having the two light-emitting layers,the light-emitting element can be made to emit white light as a whole.The same applies to a light-emitting element having three or morelight-emitting layers.

<Electron-Transport Layer 704>

The electron-transport layer 704 is a layer which contains a substancehaving a high electron-transport property.

The substance having a high electron-transport property is an organiccompound whose electron-transport property is higher than itshole-transport property; particularly, it is preferable that theelectron mobility of the substance having a high electron-transportproperty be greater than or equal to 10⁻⁶ cm²/Vs.

As the substance having a high electron-transport property, a metalcomplex having a quinoline skeleton or a benzoquinoline skeleton, suchas Alq or BAlq, a metal complex having an oxazole-based orthiazole-based ligand, such as bis[2-(2-hydroxyphenyl)benzoxazolato]zinc(abbreviation: Zn(BOX)₂) or bis[2-(2-hydroxyphenyl)-benzothiazolato]zinc (abbreviation: Zn(BTZ)₂), or the like can be used. Further, TAZ,BPhen, BCP, or the like can also be used.

<Electron-Injection Layer 705>

The electron-injection layer 705 is a layer which contains a substancehaving a high electron-injection property.

As the substance having a high electron-injection property, an alkalimetal such as lithium, an alkaline earth metal such as cesium orcalcium, or a compound thereof such as lithium fluoride, cesiumfluoride, calcium fluoride, or lithium oxide can be used. Further, arare earth metal compound such as erbium fluoride can also be used. Anyof the above-described substances for the electron-transport layer 704can also be used.

The hole-injection layer 701, the hole-transport layer 702, thelight-emitting layer 703, the electron-transport layer 704, and theelectron-injection layer 705 which are described above can each beformed by an evaporation method (e.g., a vacuum evaporation method), anink-jet method, a coating method, or the like.

<Charge Generation Layer 709>

The charge generation layer 709 shown in FIG. 6B can be formed using theabove-described composite material. The charge generation layer 709 mayhave a stacked-layer structure including a layer containing thecomposite material and a layer containing another material. In thatcase, as the layer containing another material, a layer containing anelectron donating substance and a substance having a highelectron-transport property, a layer formed of a transparent conductivefilm, or the like can be used.

<Composite Material Layer 708>

For the composite material layer 708 shown in FIG. 6C, theabove-described composite material containing an organic compound havinga high hole-transport property and an electron acceptor can be used.

<Electron-Injection Buffer Layer 706>

For the electron-injection buffer layer 706, a substance having a highelectron-injection property, such as an alkali metal, an alkaline earthmetal, a rare earth metal, or a compound of any of the above metals(including an oxide such as lithium oxide, a halide, and a carbonatesuch as lithium carbonate or cesium carbonate) can be used.

Further, in the case where the electron-injection buffer layer 706contains a substance having a high electron-transport property and adonor substance, the donor substance is preferably added so that themass ratio of the donor substance to the substance having a highelectron-transport property is from 0.001:1 to 0.1:1. As the donorsubstance, an organic compound such as tetrathianaphthacene(abbreviation: TTN), nickelocene, or decamethylnickelocene can be usedas well as an alkali metal, an alkaline earth metal, a rare earth metal,or a compound of any of the above metals. As the substance having a highelectron-injection property, a material similar to any of theabove-described materials for the electron-transport layer 704 can beused.

<Electron-Relay Layer 707>

The electron-relay layer 707 contains a substance having a highelectron-transport property and is formed so that the LUMO level of thesubstance having a high electron-transport property is located betweenthe LUMO level of the acceptor substance contained in the compositematerial layer 708 and the LUMO level of the substance having a highelectron-transport property contained in the electron-transport layer704. In the case where the electron-relay layer 707 contains a donorsubstance, the donor level of the donor substance is adjusted so as tobe located between the LUMO level of the acceptor material contained inthe composite material layer 708 and the LUMO level of the substancehaving a high electron-transport property contained in theelectron-transport layer 704. As for the specific value of the energylevel, the LUMO level of the substance having a high electron-transportproperty contained in the electron-relay layer 707 is preferably greaterthan or equal to −5.0 eV, more preferably greater than or equal to −5.0eV and less than or equal to −3.0 eV.

As the substance having a high electron-transport property contained inthe electron-relay layer 707, a phthalocyanine-based material or a metalcomplex having a metal-oxygen bond and an aromatic ligand is preferablyused.

As examples of the phthalocyanine-based material for the electron-relaylayer 707, specifically, CuPc, PhO-VOPc (Vanadyl2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine), and the like can begiven.

As the metal complex having a metal-oxygen bond and an aromatic ligandfor the electron-relay layer 707, a metal complex having a metal-oxygendouble bond is preferably used. The metal-oxygen double bond has anacceptor property (properties of high electron acceptability), whichfacilitate transfer (donation and acceptance) of electrons.

As the metal complex having a metal-oxygen bond and an aromatic ligand,a phthalocyanine-based material is preferable. In particular, a materialin which a metal-oxygen double bond is more likely to act on anothermolecular in terms of a molecular structure and having a high acceptorproperty is preferable.

As the phthalocyanine-based material, a phthalocyanine-based materialhaving a phenoxy group is preferable. Specifically, a phthalocyaninederivative having a phenoxy group, such as PhO-VOPc, is preferable. Thephthalocyanine derivative having a phenoxy group is soluble in asolvent, and thus has a merit of easy handling for formation of alight-emitting element. In addition, the phthalocyanine derivativehaving a phenoxy group, which is soluble in a solvent, also has a meritof easy maintenance of an apparatus for forming its film.

The electron-relay layer 707 may contain a donor substance. As examplesof the donor substance, materials similar to the donor materials for theelectron-injection buffer layer 706 can be given. The donor substancecontained in the electron-relay layer 707 facilitates electron transfer,enabling the drive voltage of the light-emitting element to bedecreased.

In the case where the donor substance is contained in the electron-relaylayer 707, as for the substance having a high electron-transportproperty, a substance having a LUMO level higher than the acceptor levelof the acceptor substance contained in the composite material layer 708can be used as well as the materials described above. As for thespecific energy level, the LUMO level is preferably greater than orequal to −5.0 eV, more preferably greater than or equal to −5.0 eV andless than or equal to −3.0 eV. As examples of such a material, aperylene derivative such as 3,4,9,10-perylenetetracarboxylic dianhydride(abbreviation: PTCDA), a nitrogen-containing condensed aromatic compoundsuch as pirazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile(abbreviation: PPDN), and the like can be given. The nitrogen-containingcondensed aromatic compound is preferable for the electron-relay layer707 because of its stability.

Through the above, the EL layer of this embodiment can be formed.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 6

In this embodiment, using FIGS. 7A to 7E, FIG. 8, and FIGS. 9A to 9C,description is given of examples of a variety of electronic devices andlighting devices to each of which a light-emitting device of oneembodiment of the present invention can be applied.

The light-emitting device of one embodiment of the present invention hashigh reliability and the border thereof can be slim. Thus, an electronicdevice and a lighting device each of which has high reliability andwhose border can be slim can be achieved by application of thelight-emitting device of one embodiment of the present invention.

Examples of the electronic devices to which the light-emitting device isapplied are television devices (also referred to as TV or televisionreceivers), monitors for computers and the like, cameras such as digitalcameras and digital video cameras, digital photo frames, mobile phones(also referred to as portable telephone devices), portable gamemachines, portable information terminals, audio playback devices, largegame machines such as pin-ball machines, and the like. Specific examplesof these electronic devices and the lighting device are illustrated inFIGS. 7A to 7E, FIG. 8, and FIGS. 9A to 9C.

FIG. 7A illustrates an example of a television device. In a televisiondevice 7100, a display portion 7103 is incorporated in a housing 7101.Images can be displayed on the display portion 7103 to which thelight-emitting device of one embodiment of the present invention can beapplied. Application of the light-emitting device of one embodiment ofthe present invention to the display portion 7103 enables achievement ofa television device having high reliability and a slim border. In FIG.7A, the housing 7101 is supported by a stand 7105.

The television device 7100 can be operated by an operation switch of thehousing 7101 or a separate remote controller 7110. With operation keys7109 of the remote controller 7110, channels and volume can becontrolled to control images displayed on the display portion 7103. Theremote controller 7110 may be provided with a display portion 7107 onwhich data output from the remote controller 7110 is displayed.

The television device 7100 is provided with a receiver, a modem, or thelike. With the receiver, a general television broadcast can be received.Furthermore, the television device 7100 can be connected to acommunication network by wired or wireless connection via the modem,which enables one-way (from a transmitter to a receiver) or two-way(between a transmitter and a receiver, between receivers, or the like)data communication.

FIG. 7B illustrates a computer, which includes a main body 7201, a bezel7202, a display portion 7203, a keyboard 7204, an external connectionport 7205, a pointing device 7206, and the like. The light-emittingdevice of one embodiment of the present invention is applied to thedisplay portion 7203 in this computer. Application of the light-emittingdevice of one embodiment of the present invention to the display portion7203 enables achievement of a computer having high reliability and aslim border.

FIG. 7C illustrates a portable game machine, which includes twohousings, a housing 7301 and a housing 7302, which are connected with ajoint portion 7303 so that the portable game machine can be opened andfolded. A display portion 7304 is incorporated in the housing 7301 and adisplay portion 7305 is incorporated in the housing 7302. In addition,the portable game machine illustrated in FIG. 7C has a speaker portion7306, a recording medium insertion portion 7307, an LED lamp 7308, aninput means (an operation key 7309, a connection terminal 7310, a sensor7311 (a sensor of measuring force, displacement, position, speed,acceleration, angular velocity, rotational frequency, distance, light,liquid, magnetism, temperature, chemical substance, sound, time,hardness, electric field, current, voltage, electric power, radiation,flow rate, humidity, gradient, oscillation, odor, or infrared rays), anda microphone 7312), and the like. Needless to say, the structure of theportable game machine is not limited to the above as long as thelight-emitting device of one embodiment of the present invention is usedfor at least either one or both of the display portion 7304 and thedisplay portion 7305, and can have any other accessory as appropriate.Application of the light-emitting device of one embodiment of thepresent invention to the display portion 7304 and/or the display portion7305 enables achievement of a highly reliable portable game machinewhose border is slim. The portable game machine illustrated in FIG. 7Chas a function of reading out a program or data stored in a storagemedium to display it on the display portion, or a function of sharinginformation with another portable game machine by wirelesscommunication. The portable game machine illustrated in FIG. 7C can havea variety of functions without limitation to the above.

FIG. 7D illustrates an example of a mobile phone. A mobile phone 7400has a display portion 7402 incorporated in a housing 7401, operationbuttons 7403, an external connection port 7404, a speaker 7405, amicrophone 7406, and the like. The light-emitting device of oneembodiment of the present invention is applied to the display portion7402 in the mobile phone 7400. Application of the light-emitting deviceof one embodiment of the present invention to the display portion 7402enables achievement of a highly reliable mobile phone whose border isslim.

Through a touch on the display portion 7402 of the mobile phone 7400illustrated in FIG. 7D with a finger or the like, data can be input intothe mobile phone 7400. Further, operations such as making a call andcreating e-mail can be performed by a touch on the display portion 7402with a finger or the like.

There are mainly three screen modes of the display portion 7402. Thefirst mode is a display mode mainly for displaying images. The secondmode is an input mode mainly for inputting data such as text. The thirdmode is a display-and-input mode in which two modes of the display modeand the input mode are combined.

For example, in the case of making a call or creating an e-mail, thetext input mode mainly for inputting text is selected for the displayportion 7402 so that text displayed on its screen can be input. In thiscase, it is preferable to display a keyboard or number buttons on almostthe entire screen of the display portion 7402.

Further, a detection device including a sensor for detectinginclination, such as a gyroscope or an acceleration sensor, is providedinside the mobile phone 7400, with which display on the screen of thedisplay portion 7402 can be automatically changed in response to thedetermined orientation of the mobile phone 7400 (whether the mobilephone is placed horizontally or vertically for a landscape mode or aportrait mode).

The screen mode is switched by touching the display portion 7402 oroperating the operation button 7403 of the housing 7401. The screen modecan also be switched depending on the kind of image displayed on thedisplay portion 7402. For example, when the signal of an image displayedon the display portion is a signal of moving image data, the screen modeis switched to the display mode, whereas when the signal is a signal oftext data, the screen mode is switched to the input mode.

Moreover, in the input mode, a signal detected by an optical sensor inthe display portion 7402 can be detected, whereby the screen mode may becontrolled so as to be switched from the input mode to the display modein the case where input by touching the display portion 7402 is notperformed for a specified period.

The display portion 7402 may function as an image sensor. For example,an image of a palm print, a fingerprint, or the like is taken by touchon the display portion 7402 with the palm or finger, whereby personalauthentication can be performed. Further, by using a backlight or asensing light source which emits a near-infrared light in the displayportion, an image of a finger vein, a palm vein, or the like can betaken.

FIG. 7E illustrates a desk lamp including a lighting portion 7501, ashade 7502, an adjustable arm 7503, a support 7504, a base 7505, and apower supply 7506. The light-emitting device of one embodiment of thepresent invention is applied to the lighting portion 7501 of the desklamp. Application of the light-emitting device of one embodiment of thepresent invention to the lighting portion 7501 enables achievement of ahighly reliable desk lamp whose border is slim. The lamp includes aceiling light, a wall light, and the like in its category.

FIG. 8 illustrates an example in which the light-emitting device of oneembodiment of the present invention is applied to an indoor lightingdevice 811. The area of the light-emitting device of one embodiment ofthe present invention can be scaled up and the reliability and border ofthe light-emitting device of one embodiment of the present invention arehigh and slim, respectively, which enables application to a large-arealighting device. Furthermore, the light-emitting device can be used as aroll-type lighting device 812. As illustrated in FIG. 8, a desk lamp813, which is described in FIG. 7E, may also be used in a room providedwith the interior lighting device 811.

FIGS. 9A and 9B illustrate a foldable tablet terminal. In FIG. 9A, thetablet terminal is opened, and includes a housing 9630, a displayportion 9631 a, a display portion 9631 b, a display-mode switchingbutton 9034, a power button 9035, a power-saving-mode switching button9036, a clip 9033, and an operation button 9038.

Part of the display portion 9631 a can form a touch panel region 9632 a,in which data can be input by touching operation keys 9037 which aredisplayed. Although a structure in which a half region in the displayportion 9631 a has only a display function and the other half region hasa touch panel function is shown as an example in FIG. 9A, the displayportion 9631 a is not limited to this structure. The entire area of thedisplay portion 9631 a may have a touch panel function. For example,keyboard buttons are displayed on the entire screen of the displayportion 9631 a such that the entire screen of the display portion 9631 afunctions as a touch panel, whereas the display portion 9631 b can beused as a display screen.

Like the display portion 9631 a, part of the display portion 9631 b canform a touch panel region 9632 b. Further, a switching button 9639 forshowing/hiding a keyboard of the touch panel can be touched with afinger, a stylus, or the like, so that keyboard buttons can be displayedon the display portion 9631 b.

Touch input can be performed concurrently on the touch panel regions9632 a and 9632 b.

The display-mode switching button 9034 can switch the displayorientation (e.g., between landscape mode and portrait mode) and selecta display mode (switch between monochrome display and color display),for example. With the power-saving-mode switching button 9036, theluminance of display can be optimized in accordance with the amount ofexternal light when the tablet is in use, which is detected with anoptical sensor incorporated in the tablet. The tablet may include anyanother detection device such as a sensor for detecting orientation(e.g., a gyroscope or an acceleration sensor) as well as the opticalsensor.

FIG. 9A illustrates an example in which the display portion 9631 a andthe display portion 9631 b have the same display area; however, withoutlimitation thereon, one of the display portions may be different fromthe other display portion in size or display quality. For example, oneof them may be a display panel that can display higher-definition imagesthan the other.

In FIG. 9B, the tablet terminal is folded, which includes the housing9630, a solar battery 9633, a charge and discharge control circuit 9634,a battery 9635, and a DCDC converter 9636. FIG. 9B illustrates anexample in which the charge and discharge control circuit 9634 includesthe battery 9635 and the DCDC converter 9636.

Since the tablet terminal can be folded in two, the housing 9630 can beclosed when the tablet is not in use. Thus, the display portions 9631 aand 9631 b can be protected, thereby providing a tablet terminal withhigh endurance and high reliability for long-term use.

In addition, the tablet terminal illustrated in FIGS. 9A and 9B can havea function of displaying a variety of data (e.g., a still image, amoving image, and a text image), a function of displaying a calendar, adate, the time, or the like on the display portion, a touch-inputfunction of operating or editing the data displayed on the displayportion by touch input, a function of controlling processing by avariety of software (programs), and the like.

The solar battery 9633, which is attached on the surface of the tabletterminal, supplies electric power to a touch panel, a display portion,an image signal processor, and the like. The solar cell 9633 ispreferably provided on one or two surfaces of the housing 9630, becausethe battery 9635 can be charged efficiently. A lithium ion battery canbe used as the battery 9635, which has a merit in reduction in size orthe like.

The structure and the operation of the charge and discharge controlcircuit 9634 illustrated in FIG. 9B are described using a block diagramin FIG. 9C. FIG. 9C illustrates the solar battery 9633, the battery9635, the DCDC converter 9636, a converter 9637, switches SW1 to SW3,and the display portion 9631. The battery 9635, the DCDC converter 9636,the converter 9637, and the switches SW1 to SW3 are included in thecharge and discharge control circuit 9634 in FIG. 9B.

First, an example of operation in the case where power is generated bythe solar battery 9633 using external light is described. The voltage ofpower generated by the solar battery is raised or lowered by the DCDCconverter 9636 to a voltage for charging the battery 9635. Then, whenthe power from the solar battery 9633 is used for the operation of thedisplay portion 9631, the switch SW1 is turned on and the voltage of thepower is raised or lowered by the converter 9637 to a voltage needed forthe display portion 9631. On the other hand, when display on the displayportion 9631 is not performed, the switch SW1 is turned off and theswitch SW2 is turned on so that the battery 9635 is charged.

In this embodiment, the solar battery 9633 is described as an example ofa power generation means; however, there is no particular limitation ona way of charging the battery 9635, and the battery 9635 may be chargedwith another power generation means such as a piezoelectric element or athermoelectric conversion element (Peltier element). For example, thebattery 9635 may be charged with a non-contact power transmission modulewhich is capable of charging by transmitting and receiving power bywireless (without contact), or another charging means may be used incombination.

As described above, electronic devices and lighting devices can beobtained by application of the light-emitting device of one embodimentof the present invention. The applicable range of the light-emittingdevice of one embodiment of the present invention is so wide that thelight-emitting device can be applied to electronic devices in any field.

The structure described in this embodiment can be combined with anystructure described in any of the above embodiments as appropriate.

This application is based on Japanese Patent Application serial no.2011-260218 filed with Japan Patent Office on Nov. 29, 2011, the entirecontents of which are hereby incorporated by reference.

1. (canceled)
 2. A method for manufacturing a sealed structure,comprising the steps of: attaching a tape over a substrate; applying apaste along a side surface of the tape; baking the paste to from a glasslayer; disposing a counter substrate over the glass layer; andirradiating the glass layer with laser light, wherein the glass layer isin contact with the substrate and the counter substrate.
 3. The methodfor manufacturing a sealed structure according to claim 2, furthercomprising a step of removing the tape before the glass layer is formed.4. The method for manufacturing a sealed structure according to claim 2,wherein a beam diameter of the laser light is greater than or equal to awidth of the glass layer.